Jack



N 1929 A. L. JOHNSON 1,735,839

JACK

Original Filed Nov. 17, 1924 Patented. Nov. 12, 1929 ALVIN L. JOHNSON, OF WORCESTER, MASSACHUSETTS, ASSIGNOR T WALKE R MANU- FACTURLNG COMPANY, OF RACINE, WISCONSIN, A CORPORATION OF WISCONSIN JACK Original application filed November 17, 1924, Serial No. 750,231. Divided and this application filed January 14, 1927.-

This invention relates to a jack of the screv type capable of general use but particularly adapted for automobiles.

The principal object of the invention is to provide a simplified and inexpensive jack of this type in which the work rest can be raised from a comparatively low elevation to a higher position than is possible with most forms of screw acks now on the market, and which can lower the load to a point below that at which the load was located when the jack originally started to raise it ofi' the ground.

The invention also involves improvements in the details of construction and combinations of parts that will appear.

This application is a division of my co pending application 750,231, filed November 17,1924.

Reference is to be had to the accompanying drawings, in which Fig. 1 is a central vertical sectional view of a preferred embodiment of this invention;

Fig. 2 is a plan of the same with the cover and certain other parts removed;

Fig. 3 is a view similar to Fig. 1 showing the jack expanded;

In the use of balloon and other oversize tires on automobiles, it is necessary to have a wider range of movement in a jack than has been the case heretofore and many jacks that have been satisfactory with ordinary tires are practicaiiy discarded at the present time because they do not have this range of motion. -'lhis is particularly the case with screw jacks because a screw can be raised a distance equal only to its own length. Therefore an ordinary screw jack expanded cannot be more than twice as high as it is when it is let down. By my invention ll can get a jack in which it is aiinost three times as high when expanded it is when contracted to its smallest compass and in which both screws can he raised to the full length by turning the handle as long as there is a ioad on the jack.

liow referring to the drawings, Ii provide If. standard or "frame with a suitable base and with cyiindrical chamber 11 centrally disposed and arranged vertically down through the frame. This is closed at the bot- Serial No. 161,084.

tom by a steel disc 12. This cylindrical chamber 11 is provided with two longitudinal guides or grooves 13 oppositely disposed preferably and extending from the bottom to the top of the cylindrical chamber. These guides are shown as grooves each having a fiat wall constituting a rib. lVithin this cylindrical passage I mount a screw or sleeve which I callthe outer screw. This preferably is providedwith a square thread arranged left handed. It fits in the chamber 11 sothat it can move up and down therein. Near the bottomthis'screw is provided with a pair of opposite spring pressed longitudinally shiftable PIIIS 31 projecting into the guides 12- to prevent the rotation of the screw as it is raised the pins 31 reach the top of the casing so as to come into engagement with the cams 35 they will compress going in one direction,.

but in going in the other direction thev will come up against the radial flat surface bf the guide 13 and cause the screw to stop turning and to descend in the casing' On the screw 15 Li arrange a nut or internah ly threaded sleeve it) iitting the screw and obviously adapted to raise it hv the turning of the nut on account of the pin and guide con struction just described. Any means can be employed for turning the nut hut have shown it as provided with an integral gear 19 meshing with a bevel gear 20 on a shaft 21. which can be rotated by a wrench or handle as may he desired. The casing has a cover 22 against winch the nut eiierts its thrust.

The screw 15 is hollow and provided with an internai square screw thread going in the same way as theeaternal screw thread for receiving a telescoping work rest screw 28. The screws are both preferably square threaded and left handed; On the top of this screw 28 is a work rest 29 which is fixed on the screw.

Now in the operationof the device, the operator raises or lowers the screw 28 by turning it until he gets approximately the right adjustment. Then he moves it under the work 30, as shown in Fig. 1, and turns the shaft 21 in the right direction to raise the screw 15 in the frame. When the screw 15 reaches such a point that the pins encounter the upper cams 35, this screw 15 will immediately and automatically commence to turn Without any change in the direction of rotation or other voluntary movement on the part of the operator. It turns in the direction of the arrow in Fig. 2 and immediately, on account of the fact that the screw 28 is not free to turn, that screw will commence to rise. This position of the parts is shown in Fig. 3. get almost the total height of the frame of the jack repeated in the screw 15 and then again in the screw 28, so that I get a total elevation of almost three times the height of the standard or frame.

Starting on the-downward motion with the parts in the position shown in Fig. 3, turning the shaft 21 in the opposite direction, the nut 18 will cause the screw 15 to turn withit on account of the thrust of the nut against the cover. This action cannot proceed for more than one halfa revolution because within that time both of the pins 31 will come around into contact with the flat sides of the guides 13 and prevent the further rotation of the screw. The nut continues to rotate and consequently the screws will descend without turning guided by the guides 13. This brings the work rest down a distance equal to the length of the screw 15.

It will be seen that the outer screw constitutes an internally t'l'ireaded' sleeve for operating the inner screw. The spring between the pins slightly resists the rotation of the sleeve and the side of the guide constitutes a vertical rib for engaging the spring pin and limiting its rotation. When the sleeve is turned to a certain position the cam will render the spring resistance inoperative and the pin will engage the guide and positively prevent further rotation of the sleeve in one direction.

Although i have illustrated and described only one form of the invention 1 am aware of the fact that modifications can be made therein by any person skilled in the art withv out departing from the scope of the invention as expressed in the claims. Therefore I do not wish to be limited to all the details of construction herein shown and described but what I do claim is:

l. 'A jack, comprising main and secondary screws, a standard for said screws. a r0tatable nut for the main screw, a shiftable pin carried by the main screw, and stop and can:

It will been seen that 1 means within said standard engageable by said pin adapted to withhold the main screw from rotation during part of its travel and to permit rotation thereof at end end of its travel,

2. A jack, comprising a standard and a pair of telescopic screws mounted thereon, a rotatable nut adapted to raise and lower said screws, a spring-pressed pin carried by one'of said screws, and said standard having a guide and eccentric surfaces adapted to be engaged by said pin in raising and lowering said screws.

3. A lifting jack comprising a standard, an internally threaded operating sleeve mounted thereon, means for causing rotation of said sleeve; a lifting member threadedly mounted within said sleeve; means for restraining rotation of said threaded member with respect to the said sleeve comprising stop means carried. by said standard, a cooperating restraining member carried by the said lifting member. and cam means associated with the said stop member for rendering the restraining means inoperative with respect to the said stop means'when the threaded member has reached a predetermined positioning.

4. A lifting jack comprisinga standard, a threaded sleeve rotatably supported by said standard, means for rotating said sleeve; a threaded member rotatably mounted within said threaded sleeve; a threaded stem rotatably mounted within said threaded member; spring pressed means carried by said threaded member, and cooperating restraining means carried by the said standard, for controlling movement of the said threaded member and threaded stem, to-effect successive raising or lowering of the said members with respect to the standard.

5. A lifting jack comprising a standard, a threaded sleeve-rotatably supported by said standard, means for rotating said sleeve; a threaded member rotatably mounted within said threaded sleeve; a threaded. stem rotatably mounted within said threaded member; a spring pressed means carried by said threaded member, and cooperatin restraining means carried by the said stan ard, for controlling movement of the said threaded member and threaded stem with respect to each other, to effectsuccessive raising or lowering of the said members with respect to the standard, and means carried by said standard for rendering the said restraining means inoperatii e when the said threaded member has reached a predetermined vertical positioning relative to the standard.

ALVIN L. JOHNSON.

CERTIFICATE ()F CORRECTION.

Patent No. 1,735, 839. Granted November 12, 1929, to

ALVIN L. JGHNSQN.

It is hereby certified that error appears in the above numbered patent requiring correction as follows: in the drawing, strike out Figures 4 and 5; page 2, line 69, claim 1, for the word "end" read "the"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Giiice.

Signed and sealed this 14th day of January, A. D, 1930.

M. J. Moore, (Seal) Acting Commissioner of Patents. 

